As this kind of liquid sealed vibration isolating device, there is publicly known the art of the type that a damping orifice for connecting a primary liquid chamber and a secondary liquid chamber is provided in a partition member which separates the primary liquid chamber and the secondary liquid chamber, and a movable diaphragm is provided for absorbing liquid pressure fluctuation of the primary liquid chamber.
There is also publicly known the art that a leg portion a tip of which projects outward in a radial direction is provided on a lower surface (a secondary liquid chamber side, and the same shall apply hereinafter.) of the movable diaphragm, and the tip of the leg portion is pressed against a pressed portion provided on a support member of the movable diaphragm. In this case, the pressed portion is formed with a taper surface which protrudes toward a center side of the secondary liquid chamber, and at the time of large deformation of the movable diaphragm the leg portion is compressed harder to increase a spring constant of the movable diaphragm (see a patent reference 1).
Further, there is publicly known the art that a damping orifice and an idle orifice are provided and, when idling, a secondary liquid chamber side opening of the idle orifice is opened through an opening and closing valve to produce resonance within the idle orifice thereby to damp the input of idle vibration.